:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #6b7280;
  --border: #d1d5db;
  --accent: #2563eb;
  --accent-fg: #ffffff;
  --ok-bg: #ecfdf5;
  --ok-fg: #065f46;
  --err-bg: #fef2f2;
  --err-fg: #991b1b;
  --code-bg: #f3f4f6;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0c0e;
    --fg: #e5e7eb;
    --muted: #9ca3af;
    --border: #2a2d33;
    --accent: #3b82f6;
    --ok-bg: #052e1f;
    --ok-fg: #6ee7b7;
    --err-bg: #2a1212;
    --err-fg: #fca5a5;
    --code-bg: #15171b;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg); color: var(--fg);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Roboto, sans-serif; }
main { max-width: 560px; margin: 0 auto; padding: 18px 20px 64px; }
h1 { font-size: 24px; margin: 0 0 4px; }
.sub { color: var(--muted); margin: 0 0 24px; }

.who { display: flex; justify-content: space-between; align-items: center;
  font-size: 12px; color: var(--muted); margin-bottom: 12px; }
.who a { color: inherit; }

form { display: grid; gap: 14px; }
label { display: grid; gap: 6px; }
label > span { font-size: 13px; color: var(--muted); }

input, select, button {
  font: inherit;
  padding: 12px 14px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
  border-radius: 10px;
  width: 100%;
}
input:focus, select:focus { outline: 2px solid var(--accent); outline-offset: 0; border-color: transparent; }
input[readonly] { background: var(--code-bg); }

#sn { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  letter-spacing: 0.08em; text-transform: uppercase; }

details { border: 1px solid var(--border); border-radius: 10px; padding: 8px 12px; }
details > summary { cursor: pointer; color: var(--muted); font-size: 13px; padding: 4px 0; }
details[open] > label { margin-top: 10px; }

button { background: var(--accent); color: var(--accent-fg); border: 0; font-weight: 600; cursor: pointer; }
button:disabled { opacity: 0.5; cursor: not-allowed; }
button:active { transform: translateY(1px); }

#copy { width: auto; padding: 10px 14px; }
.copyrow { display: flex; gap: 8px; }
.copyrow input { flex: 1; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 13px; }

section { margin-top: 22px; padding: 16px; border-radius: 12px; border: 1px solid var(--border); }
.row { display: flex; gap: 12px; align-items: center; }
.meta { font-size: 12px; color: var(--muted); margin-top: 2px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }

.spinner {
  width: 22px; height: 22px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  flex: 0 0 auto;
}
@keyframes spin { to { transform: rotate(360deg); } }

#result { background: var(--ok-bg); border-color: transparent; }
#result .ok { color: var(--ok-fg); font-weight: 600; margin-bottom: 12px; }
#result a { color: var(--ok-fg); display: inline-block; margin-top: 10px; }

#error { background: var(--err-bg); border-color: transparent; }
.err { color: var(--err-fg); font-weight: 600; }
#error a { color: var(--err-fg); display: inline-block; margin-top: 8px; }

footer { margin-top: 32px; color: var(--muted); text-align: center; }
footer a { color: inherit; }